In a power switching device such as a breaker, there is known an operating time prediction apparatus for predicting and controlling an operating time. For example, in Patent Document 1, as the apparatus for predicting the operating time in the power switching device such as the breaker and its method, the following are disclosed: when the breaker performs an opening or closing operation, an operating time and an environmental condition thereof are stored, and an operating characteristic parameter thereof is estimated by functional approximation of a history thereof, and hence a next operating time is predicted from the estimated operating characteristic parameter and the current environmental condition.
Meanwhile, an SF6 gas typically used in the breaker has a property of freezing in a low temperature region, and thus the operating time required for the opening/closing operation varies largely.
In addition, the following matters are known in the breaker: the operating time gradually changes due to a time-dependent change (change with time) caused by abrasion of a contact thereof and so on, and there exists an amount of variation in the operating time according to a normal distribution. Further, it is also known that there is an individual difference in the time-dependent change rate and/or the amount of variation of them.